Related papers: On the Accuracy of Galileo's Observations
The GREAT observations need frequency-selective calibration across the passband for the residual atmospheric opacity at flight altitude. At these altitudes the atmospheric opacity has both narrow and broad spectral features. To determine…
Very Long Baseline Interferometry (VLBI) observations can provide the position of compact radio sources with an accuracy of order 50 micro-arcseconds. This is sufficient to measure the trigonometric parallax and proper motions of any object…
The description of an observer's measurement in general relativity and the standard model of particle physics is closely related to the spacetime metric. In order to understand and interpret measurements, which test the metric structure of…
The empirical law of Gladstone-Dale is insufficient for high-precision studies using the refractivity of a gas: this is not exactly proportional to its density, and the gas may not be properly described as perfect. An optical Mariotte…
The performance of an adaptive optics (AO) system on a 100m diameter ground based telescope working in the visible range of the spectrum is computed using an analytical approach. The target Strehl ratio of 60% is achieved at 0.5um with a…
In the late 1620s the Neapolitan telescope maker Francesco Fontana was the first to observe the sky using a telescope with two convex lenses, which he had manufactured himself. Fontana succeeded in drawing the most accurate maps of the…
Gravitational lensing is a powerful tool to detect compact matter on very different mass scales. Of particular importance is the fact that lensing is sensitive to both luminous and dark matter alike. Depending on the mass scale, all lensing…
We employ VLTI GRAVITY to resolve, for the first time, the two images generated by a gravitational microlens. The measurements of the image separation \theta_{-,+}=3.78 +/- 0.05 mas, and hence the Einstein radius \theta_E =1.87 +/- 0.03…
The gravitational waves (GWs) has been a topic of interest for its versatile capabilities of probing several aspects of cosmology and early Universe. Gravitational lensing enhances further the extent of this sort of waves and upgrade our…
We have measured angular dimensions of 312 planetary nebulae from their images obtained in Halpha (or Halpha + [NII]). We have applied three methods of measurements: direct measurements at the 10% level of the peak surface brightness,…
Deflection of light due to massive objects was predicted by Einstein in his General Theory of Relativity. This deflection of light has been calculated by many researchers in past, for spherically symmetric objects. But, in reality, most of…
In spite of all the attempts conducted to improve the accuracy of the gravity wave detectors in recent years, no method has been successful to measure these waves up to now. Most of these detectors and laser interferometers work based on…
The objective reality of the Earth's motion about the Sun was finally proven observationally by Bradley (1727) when he correctly explained the ~20'' annual, elliptical motions of stars as being due to aberration of starlight caused by the…
A method of detecting of short scalar gravitational waves with a wavelength of ~ 0.5 micrometers is proposed, in contrast to LIGO Project, aimed at detecting of long quadrupole gravitational waves with a wavelength in interval from 43 till…
A general principle of non-equivalence for bodies and observers in different G potentials (GP) was derived from correspondence of the Einstein's equivalence principle either with optical physics or with gravitational experiments in which…
Typical applications of gravitational lensing use the properties of electromagnetic or gravitational waves to infer the geometry through which those waves propagate. Nevertheless, the optical fields themselves - as opposed to their…
The angular size of a star is a critical factor in determining its basic properties. Direct measurement of stellar angular diameters is difficult: at interstellar distances stars are generally too small to resolve by any individual imaging…
We entertain the use of light dependent resistors as a viable option as measuring sensors in optics laboratory experiments or classroom demonstrations. The main advantages of theses devices are essentially very low cost, easy handling and…
We first briefly review the adventure of scale invariance in physics, from Galileo Galilei, Weyl, Einstein, and Feynman to the revival by Dirac (1973) and Canuto et al. (1977). We then gather concrete observational evidence that…
The history of astrometry, the branch of astronomy dealing with the positions of celestial objects, is a lengthy and complex chronicle, having its origins in the earliest records of astronomical observations more than two thousand years…